#include <bits/stdc++.h>
using namespace std;
class Solution
{
public:
  int findMaxK(vector<int> &nums)
  {
    unordered_map<int, bool> h;
    int ans = -1;
    for (int num : nums)
    {
      h[num] = true;
      if (h[-1 * num])
        ans = max(ans, abs(num));
    }
    return ans;
  }
};
int main()
{
  Solution s;

  return 0;
}
